Chlamydia trachomatis and Herpes Simplex Virus type 2 (HSV-2) are two very common sexually transmitted disease (STD) agents. In the US, 4 million new cases of C. trachomatis and 500,000 new cases of HSV-2 are reported annually. Epidemiological and clinical case studies indicate that double infection with HSV-2 and C. trachomatis occurs in the human population. However, the possibility that co-infection with HSV-2 and C. trachomatis might alter pathogenesis or transmission of one or both of these organisms in vivo has not been rigorously examined. The long-term goal of our laboratory is to determine whether super or double infection with C. trachomatis/HSV-2 changes transmission or disease. As a first step toward this goal, we have established a cell culture model of HSV-2/C. trachomatis co-infection. Our preliminary data demonstrate that HSV-2 super-infection profoundly effects the chlamydial developmental cycle. Chlamydial reticulate bodies (RB) in co-infected cells are swollen and diffuse, resembling persistent chlamydiae. Elementary bodies (EB) are not observed. Co-infected cells also contain numerous membrane blebs; similar structures carry a chlamydial immunodestructive antigen, lipopolysaccharide (LPS), to the surface of persistently infected cells. These data suggest a mechanism by which co-infection could increase chlamydial disease severity by releasing pro-inflammatory molecules and "hyper-activating" the inflammatory response. The immediate goal of this proposal is to test the following hypothesis: productive HSV-2 replication within C. trachomatis infected cervical epithelial cells interferes with chlamydial development and alters release of immunomodulatory molecules from co-infected cells. This hypothesis will be tested in the first 2 related, but independent, Specific Aims. Aim 1 will determine whether productive HSV-2 replication is required for induction of C. trachomatis human serovar E and murine biovar MoPn (C. muridarum) persistent morphology in co-infected cells. Aim 2 will determine whether HSV-2/C. trachomatis co-infected cells produce or release altered quantities of immunomodulatory molecules. Aim 3 will ascertain whether less-pathogenic, attenuated HSV-2 mutants can induce persistence in the human C. trachomatis serovar E as well as the murine biovar MoPn. The studies in Aim 3 will facilitate development of a murine co-infection model system. Completion of this project will narrow down the possible mechanisms by which HSV interferes with the chlamydial developmental cycle, identify immunomodulatory substances released from co-infected calls and set the stage for development of an in vivo routine co-infection model. Additionally, novel mechanisms for induction of chlamydial persistence may be identified, thus increasing our understanding of chlamydial/host cell interactions. [unreadable] [unreadable]